“Rotating Shaft Structure with Automatic Locking Mechanism,” developed by the present inventor, is disclosed in the ROC Patent No. M296586 on Aug. 21, 2006 (corresponding to the PRC Patent No. 200620001995.4), as shown in FIG. 10. The invention mainly involves inserting the shaft 101 of an axial member 10 into, in the order of, a friction disc 30, a plate connecting part 40, a cam member 50, an elastic body 60, and securingly fixed onto the main frame 20, wherein the cam member 50 comprises a fastening part 501 and a sliding part 502, and when the axial member 10 rotates, the wedge slot 502a of the sliding part 502 is driven to slide and engage into the wedge block 501a of the fastening part 501, achieving the auto-locking function.
However, the centers of the respective axle hole of the main frame 20, the friction disc 30, the plate connecting part 40, and the cam member 50 have to be aligned before they can be inserted into the axial member 10. If any axle hole is not accurately aligned with the others, the axial member 10 cannot be inserted thereinto. It is therefore a drawback which required to be overcome.